teensy 4.1 with audio adapter

A

ajlapp

Active member
I've made a custom board to generate an RTP stream using a 4.1 and the audio adapter.

The microphone seems to work well and I can here the audio over the network.

I have the line-out jack wired to a 12v speaker that has it's own mini-amp.

When I connect the speaker everything seems to stop working.

The microphone is now just noise and the speaker sounds about the same.

This same setup works fine if I only connect the output to headphones?? I'm a bit lost as this is my first audio project.

Digitally everything associated with the RTP is working...so this feels like some sort of grounding issue or other analog item that I don't understand.

I'm using this speaker:

Everything is powered from the same 12v battery.....I have a 5v converter for the teensy.

I also just noticed that when everything is connected i can hear the microphone slightly playing over the speaker....they should be independent in this setup.
 
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ajlapp said:
I have the line-out jack wired…
Click to expand...
Do you mean the headphone jack? If so, note this warning:
1758204624030.jpeg

The “ground” on the headphone jack is NOT the same as Teensy ground, and shorting it to ground usually results in no or poor output. The shield silkscreen is pretty much the only place this rather important fact is “documented”.
 
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I am aware of this....I don't have an easy way to check this currently with the system installed.

I am using the 3.5mm jack....the speaker amp uses the same line-in audio jack.

The teensy is powered by a 5v converter from the same 12v bus that the speaker amp is powered on.
 
Well if there’s no easy way, I’m afraid you’ll have to do it the hard way and uninstall it so you can post some pictures of your wiring.

I‘m still concerned by your statement that you’re “using the 3.5mm jack” … if you’re referring to the jack on the shield, and connecting that to the amp, you shouldn’t be, as you‘re already aware.
 
oh...sorry, I misspoke. I'm aware that I shouldn't short virtual ground to the main ground....I guess I wasn't aware that using the line-out jack would somehow connect these??

So if you can't use the supplied jack to connect to audio equipment what are you supposed to do?

I see now....it looks like I need to use the line out pins because the 3.5mm jack is really only for headphones. :0

I'm enjoying this adapter but it does have some quicks.

Thanks.
 
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